Using FIG. 27, an explanation of a conventional liquid delivery system that is a beer tapping device will be explained. In the case of a beer dispensing device 101A, the presence or absence of beer from each of beer kegs 102A, 102B, delivered to a dispenser 120 by way of each of beer flowpath switching valves 118, a conduit 108, and a branching valve 117 is detected by each of beer sensors 109. At first, in a situation where, for example, when a one beer keg 102A has run out of beer and is replaced with a fresh beer keg and the fresh beer keg is tapped, until the beer sensor 109 detects that there is beer, the beer flowpath switching valve 118 is switched over to a debubbling valve 119 side, to carry out discharging of bubbles in the conduit 108 through the debubbling valve 119. After the beer sensor 109 has detected the presence of beer, through a fixed time period (approximately two seconds) the bubble-discharging state is continued, and subsequently the beer flowpath switching valve 118 switches the flowpath over to the conduit 108 side. The beer from the in-use beer keg—that is, beer keg 102A or 102B—is thereby delivered to the dispenser 120 by way of the beer flowpath switching valve 118, the conduit 108, and the branching valve 117. On the other hand, if for example the beer sensor 109 on the beer keg 102A side detects that there is no beer, the branching valve 117 operates, whereby the conduit 108 on the beer keg 102B side is communicated with the dispenser 120. This results in the beer keg 102A being cut off from the conduit 108 and the beer keg 102B being connected to the conduit 108, enabling the supply of beer by the beer keg 102B following on the beer keg 102A to be carried out automatically. In this way, by means of the beer dispensing device 101A, the presence/absence of beer in a plurality of beer kegs 102A, 1028 is detected by the respective beer sensors 109, and with a keg in which the beer in its essence has gone empty being replaced in succession with a fresh beer keg without interruption, debubbling through the conduit 108 by the valve 119 at the outset of use of a fresh keg is carried out, while cutoff of the empty beer keg 102A through its conduit 108 and connection to a full beer keg 102B via its conduit 108 are carried out by the branching valve 117 without interruption, whereby, with unnecessary bubbles that arise during replacement of the beer kegs 102 being eliminated, good-quality beer may be dispensed continuously for a long period of time.